Hitherto, as a vehicle body assembling method for assembling a vehicle body by using a floor member, side members, and a roof member, there has been known a method in which jigs holding each of the members are connected to preliminarily assemble the members, and the preliminarily assembled members are welded (e.g. Patent Document 1).
According to the method, in a state wherein a floor member, side members, and a roof member are held by a floor jig, a side jig, and a roof jig, respectively, the floor jig, the side jig, and the roof jig are connected to preliminarily assemble the floor member, the side members, and the roof members. Then, while retaining the preliminarily assembled state, the jigs are carried as one piece to a plurality of stations at which the floor member, the side members, and the roof member are welded for preliminary assembling.
After completing the preliminary assembling, the jigs are disconnected and separated to be detached. Then, additional welding is carried out to complete a main body.